Magnetic catch



Feb. 19, 1963 A. w. AHLGREN MAGNETIC CATCH Filed June 7, 1961 wvsw-rcL/ fCF kl rem $44.4 J3 a W QAw-ro IQJQBY/ talented States l stens 3,97%,114 Patented Feb. 19,1963

3,073,114 MAGNETHC CATCH Axel W. Ahlgren, Rockford, lit, assignor to Ameroek Corporation, Rockford, Ill., a corporation of Illinois Filed June 7, 1961, Ser. No. 115,497 2 Claims. (Cl. 292-4515) This invention relates to a magnetic catch for holding a door or the like in a fixed position and, more particularly, to such a catch in which flat plates are disposed against opposite faces of a flat permanent magnet and project beyond one edge of the magnet to provide the pole faces of the catch.

The general object of the invention is to provide a new and improved catch of the above character which is simple in construction and inexpensive to produce.

A more specific object is to form the pole plates in a novel manner and utilize the plates as a housing for supporting and mounting the assembly as well as to provide the poles faces.

Other objects and advantages of the invention will become apparent from the following detailed description taken in connection with the accompanying drawings, in which FIGURE 1 is a side elevational view of a catch embodying the novel features of the present invention.

FIG. 2 is an enlarged perspective view of the novel catch shown in FIG. 1.

FIG. 3 is a fragmentary sectional view taken along the line 3-3 in FIG. 1.

FIG. 4 is a ditferent perspective view of the catch.

FIG. 5 is an enlarged perspective view of a strike for use with the catch.

FIG. 6 is an enlarged fragmentary sectional view taken along the line 6-6 in FIG. 4 and showing a step in the assembly of the catch.

FIG. 7 is an enlarged sectional view taken along the line 7-7 in FIG. 3.

As shown in the drawings for purposes of illustration, the invention is embodied in a magnetic assembly 16 which serves as a catch for a swinging cabinet door 11. The illustrative catch is secured on the underside of a shelf 12 near the outer edge 13 thereof and is positioned to contact a strike 14 which is fastened on the inside of the door. The strike is composed of a magnetic material such as iron or steel and, therefore, is magnetically held against the catch when the door is in the closed position.

In this instance, the strike 14 comprises a disc 15 having a center hole through which a fastener such as a screw 17 may be driven into the door. To compensate for misalignment between the strike and the catch, an annular tapered flange 18 is formed around the hole to abut against the door, and the screw first is tightened down so that the flange bites into the wood and then is backed partially out of the door. Thus, as the disc 15 contacts the catch, the disc is free to rock on the flange and align itself with the catch.

The magnetic assembly 10 includes a pair of flat and preferably generally rectangular plates 19 and 20 which are composed of magnetic material and are disposed against opposite faces of a permanent magnet 21. These plates extend outwardly past one edge 22 of the magnet and terminate in linear edges 23 disposed in a common plane to form spaced pole faces of the assembly. The magnet 21 preferably comprises a substantially rectangular wafer composed of a material in which the flat faces of the wafer are the magnetic poles. Two such materials are those sold under the trademarks Index and Plastiform.

The present invention contemplates a new and improved magnetic catch 10 which is simple in construction and inexpensive to produce. For this purpose, the pole plates 19 and 2d are formed as a unit from a single sheet of magnetic material and disposed against opposite faces of the magnet with a strap 25 integral with the plates joining the latter across one edge of the magnet, and with abutments formed on the sheet to extend inwardly over the other edges of the magnet and hold the magnet between the plates. Thus, the plates form the housing of the assembly, in addition to providing the pole faces, and means is provided for fastening at least one of the plates on the support thereby to mount the catch.

While the strap 25 integrally joining the pole plates may be made of varying widths depending upon the intended application of the catch, the strap preferably is formed with a cross-sectional area substantially less than the area of the pole faces 23. In this way, shunting of the magnetic flux through the strap is reduced and a high flux density is maintained between the pole faces. To obtain optimum rigidity of the assembly with a reduced crosssectional area, a plurality of spaced straps may be used. Herein, the plates 19 and 2d are connected by two straps 25 having a combined area substantially less than that of the faces 23 and, in the form shown in the drawings, the combined cross-sectional area of the straps is less than half the area of each of the pole faces. In the present instance, one strap is disposed adjacent each of the rear corners of the catch.

In the present instance, the abutments for preventing the magnet from shifting sideways between the plates are flanges 2.7 bent at right angles with the plate 20 to extend inwardly across the side edegs of the magnet. To present sliding of the magnet between the pole faces 23, an abutment preferably comprising an ear 2? extends inwardly from the projecting portion of at least one of the plates. Herein, similar ears 23 are struck inwardly from each of the plates.

As shown in the drawings, the means for mounting the catch on the support may be a pair of wings 29 extending laterally from opposite sides of the catch and slotted as at St to receive suitable fasteners such as screws 31. The Wings 29 are formed integrally with the plate 19 and are offset rearwardly so that the catch may be mounted with the pole faces 23 disposed a substantial distance be yond the edge 13 of the shelf 12.

The catch described above may be manufactured simply and inexpensively using mass production techniques. Initially, a flat sheet of metal is shaped as by punching to form the slotted wings 29, the flanges 27, and a rectangular cut-out 32 (FIG. 4) and notches 33 defining the straps 25 intermediate the ends of the sheet, and at the same time a. portion of metal is displaced at each end of the sheet to form the cars 28. Then the flanges 27 are bent at right angles with the sheet and the latter is bent along lines 34 into a generally U-shaped pole piece unit as shown in FIG. 6. Finally, the wafer 21 is inserted between the legs of the unit and the bends along the lines 3 2- are completed to press the plates 19 and 2% against the wafer as shown in FIG. 7. Thus, the magnetic assembly 10 is finished and the magnet is held securely in place, the plates 19 and 29 forming the pole pieces and also the housing for the assembly.

I claim as my invention:

1. In a magnetic catch, the combination of, a permanent magnet, and a pole piece unit composed of a single sheet of magnetic material and comprising plates disposed against opposite faces of said magnet said faces constituting the poles of said magnet, connecting means including at least one strap integrally joining said plate: across one edge of said magnet, abutments formed or said sheet and extending inwardly over the other edge: of said magnet to prevent shifting of the latter from be tween said plates, said plates projecting past one of said othcr edges to form spaced linear pole faces, the total 4, References Cited in the file of this patent UNITED STATES PATENTS 2,906,553 Wilson Sept. 29, 1959 2,990,210 Fremstad June 27, 1961 FOREIGN PATENTS 607,148 Great Britain Aug. 25, 1948 

1. IN A MAGNETIC CATCH, THE COMBINATION OF, A PERMANENT MAGNET, AND A POLE PIECE UNIT COMPOSED OF A SINGLE SHEET OF MAGNETIC MATERIAL AND COMPRISING PLATES DISPOSED AGAINST OPPOSITE FACES OF SAID MAGNET SAID FACES CONSTITUTING THE POLES OF SAID MAGNET, CONNECTING MEANS INCLUDING AT LEAST ONE STRAP INTEGRALLY JOINING SAID PLATES ACROSS ONE EDGE OF SAID MAGNET, ABUTMENTS FORMED ON SAID SHEET AND EXTENDING INWARDLY OVER THE OTHER EDGES OF SAID MAGNET TO PREVENT SHIFTING OF THE LATTER FROM BETWEEN SAID PLATES, SAID PLATES PROJECTING PAST ONE OF SAID OTHER EDGES TO FORM SPACED LINEAR POLE FACES, THE TOTAL CROSS-SECTIONAL AREA OF SAID CONNECTING MEANS BEING LESS THAN HALF THE AREA OF EACH OF SAID POLE FACES WHEREBY THE PRIMARY FLUX PATH OF SAID MAGNET PASSES THROUGH THE POLE FACES, AND MEANS ON SAID SHEET FOR MOUNTING SAID CATCH ON A SUPPORT. 